<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta http-equiv="X-UA-Compatible" content="IE=edge" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>光影特效</title>
    <link rel="stylesheet" href="css/circle-shadow.css" />
  </head>
  <body>
    <div class="circle"></div>
    <div class="circle"></div>
    <svg>
      <filter id="wavy">
        <feTurbulence x="0" y="0" baseFrequency="0.009" numOctaves="5" seed="2">
          <animate
            attributeName="baseFrequency"
            dur="60s"
            values="0.02;0.005;0.02"
            repeatCount="indefinite"
          >
        </feTurbulence>
        <feDisplacementMap in="SourceGraphic" scale="30"></feDisplacementMap>
      </filter>
    </svg>
  </body>
</html>
